Through the process of metabolic engineering, microbial organisms can be engineered for the production of various desirable compounds. Such engineered microbial strains and their products can be useful. For example, some microbial strains can produce chemicals from renewable feedstocks rather than from nonrenewable petroleum. Metabolic engineering has been practiced for many years, and the traditional approaches have included strategies such as random mutagenesis with selection for an over-producer or over-expression of genes either directly responsible for secondary metabolite production or genes indirectly involved in increasing metabolite production. Provided herein are engineered microbial strains with useful carbohydrate production characteristics. In some embodiments, the engineered microbial strains are designed using a genome-scale metabolic model so as to systematically select a strain with a desired phenotype.